Induration of greater than or equal to 15mm is considered positive in which population?

In the context of tuberculosis (TB) testing, particularly the Mantoux tuberculin skin test (TST), the size of induration at the injection site is crucial for interpretation. An induration of greater than or equal to 15mm is considered positive in individuals who are generally healthy and with no known risk factors for TB.

However, the specific population for whom a 15mm induration is deemed positive refers to individuals who are considered at lower risk for TB infection, but it can also apply to everyone based on their medical history and potential exposure. For those with known risk factors—such as immunocompromised individuals or those who have been in close contact with someone with active TB—a much smaller induration is typically considered significant.

To clarify, individuals with a recent history of TB, known risk factors, or those who have traveled to high-prevalence areas may have different thresholds set for what is considered a positive test result. These thresholds help ensure accurate detection and management of TB, tailored to the specific health risks of different populations. The emphasis on this question is thus more on the general population without significant risk factors, making "persons with known risk factors for TB" the accurate focus for understanding the significance of the 15mm